Internal combustion engines for powerdriven tools



INTERNAL COMBUSTION ENGINES FOR POWER-DRIVEN TOOLS Filed Dec 8, 1960 May 29, 1962 v G, H. w. DOBBERTIN 3 Sheets-Sheet l INVENTO R. GUN TH E R HEINRICH W/LHHM DOBBERTIM w M A TTO R N E YS y 9, 1962 c, H. w. DOBBERTlN 3,036,566

INTERNAL COMBUSTION ENGINES FOR POWER-DRIVEN TOOLS Filed Dec. 8, 1960 3 SheetsSheet 2 INVENTOR GUN'HgR HElNRiCH WILHELM DOBBERTIN ATTORNEY INTERNAL COMBUSTION ENGINES FOR POWER-DRIVEN TOOLS May 29, 1962 G. H. w. DOBBERTIN Filed Dec.

3 Sheets-Sheet 3 INVENTOR GUNTHER HHNRICH WILHHM DOBBERTIN BY M /M ATTORNEYS United States Patent Gfjice 3,036,566 Patented May 29, 1962 3,036,566 INTERNAL COMBUSTION ENGINES FOR I'GWER- DRIVEN TOOLS Gunther Heinrich Wilhelm Dobbertin, Gothenburg,

Sweden, assiwor to Aktiebolaget Berghorrmaskiner,

Gunnebogatan, Molndal, Sweden Filed Dec. 8, 1960, Ser. No. 74,666 Claims. (Cl. 123-195) The present invention relates to internal combustion engines for powerdriven tools, such as portable saws, and more specifically to engines of this kind having a casing which is made in two halves.

It is an object of the invention to provide a rugged engine of this type which is of comparatively simple design and therefore can be produced at a low cost.

In an engine according to the invention the casing is divided into two halves along a substantially medial plane which form the supporting structure of the engine and these halves are formed with cavities which are open towards that side of each casing half which faces the other casing half, said cavities either forming the engine crank case and a fuel container or forming a space for receiving such elements.

According to the invention, the casing halves may further be provided with cavities forming a lubricant container or a space for receiving such container.

Further objects and features of the invention will appear from the following detailed description of a preferred embodiment, applied to a portable power-driven saw, reference being had to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a casing according to the invention for the engine of a power-driven saw;

FIG. 2 is a longitudinal section taken through that plane along which the casing is divided into two halves (i.e. along line II-II in FIG. 1 and also IIII in FIG.

FIG. 3 is a longitudinal section taken along the line IIIIII in FIG. 1; and

FIG. 4 is a side view of the portable saw, partly broken and drawn to a smaller scale.

In the drawings 1 and 2 designate the two halves of a motor casing divided along the plane indicated by IIII in FIGS. 1 and 3 which is substantially the medial plane of the composite casing. A cover placed over the interconnected casing halves is indicated at 3. The casing is further provided at one end with a handle 4 which in the embodiment shown is likewise composed by two halves each made in one piece with one of the casing halves 1 and 2. To that end of the casing which is opposite the handle 4 there is attached a carrying yoke 5.

FIG. 2 shows the casing half I seen from the dividing plane (IIII in FIGS. 1 and 3). The casing half 1 is formed with cavities 6, 7 and 8 which are open at the side facing the dividing plane, and the other casing half 2 is provided with corresponding cavities 106, 107 and 108 likewise open towards the dividing plane and disposed opposite the cavities 6, 7 and 8, respectively, in the casing half 1. The cavities 6 and 106 together form a space for the cylinder 9 of the engine. The engine crank case is formed by the cavities 7 and 107. A recess 10 in the partition wall between the cavities 6 and 7 of easing half 1 and a correspondingly disposed recess 110 in the easing half 2 together form an opening for the piston rod 11. In the example shown in the drawings, the engine is a two-stroke carburettor engine with the crank case adapted as the scavenging pump. The carburettor 12, shown in broken lines in FIGS. 1 and 2 is mounted in the space under the cover 3 over an inlet port 13 communicating via a passage 14 with the crank case formed by the cavities 7 and 107.

The cavities 8 and 108 in the two casing halves 1 and 2, respectively, together form a space receiving a fuel container 15 and a container 16 for a lubricant for lubrication of the saw chain (not shown). Both containers are preferably made from a plastic material, and, as can be seen from FIG. 2, the lubricant container 16 is fitted between the fuel container 15 and the wall separating the space 8, 108 enclosing said containers from the crank case 7, 107, so as to protect the fuel container 15 from the heat emanating from the crank case. In FIG. 4, 17 and 18 indicate filler caps for the fuel and lubricant containers 15 and 16, respectively, said caps being arranged in the side wall of casing half 2. A flexible hose 19 connecting the fuel container 15 with the carburettor 12 has a portion extending into the container and provided at its free end with a filter 20 which also serves as a weight for moving the intake end of the hose towards the lowest part of the fuel container when the saw is turned into different positions. The lubricant container 16 is likewise provided with a flexible hose 21 having a filter 22 at its free end. The opposite end of the hose connects to an oil pump or the like not shown in the drawings.

The bottom of each of the cavities 7, 107 forming the crank case is provided with a depressed portion 23 and 123 respectively (FIG. 1), for receiving ball bearings for the crank shaft 24 which is passed through central openings 25 and 125, respectively, in said depressed portions. In the casing half 1 the space 26 between the cavities and the outer side wall of the casing half contains a clutch 27 on the end of the crank shaft 24 for transmitting the crank shaft rotary movement to the saw chain. The saw chain and its drive means do not form any part of the present invention and are therefore not shown in the drawings. The opposite end portion of the crank shaft 24 projects into a space 28 in the casing half 2 between the outer side wall and the cavities thereof and carries a fan wheel 29 for blowing cooling air to the cylinder-containing space 6, 106' which communicates with the space 28.

Although the fuel and lubricant containers 15 and 16, respectively, have been described above as arranged within a common compartment formed by the cavities 8 and 108, the casing halves 1 and 2 may equally well be formed with separate cavities for separately receiving the two containers. Also the containesr may be made of any suitable material, such as sheet metal or the like. It is further possible, by connecting the two casing halves in a fluid-tight manner, to let the spaces formed by such cavities directly serve as containers for the fuel and lubricant. Further the cavities forming the crank case may be shaped for receiving a separately formed crank case unit. Other variations and modifications are of course conceivable within the scope of the invention which is not limited to the embodiment hereinbefore described and shown in the accompanying drawings.

What I claim is:

1. An internal combustion engine for portable powerdriven tools and the like, comprising a casing enclosing said engine and forming the supporting structure thereof, said casing being divided into two halves along a substantially medial plane, each of said halves having cavities formed therein which are open towards said plane, said cavities forming the engine crank case and a fuel container.

2. An internal combustion engine for portable powerdriven tools and the like, comprising a casing enclosing said engine and forming the supporting structure thereof, said casing being divided into two halves along a substantially medial plane, each of said halves having cavities formed therein which are open towards said plane, said cavities forming the engine crank case and a space for receiving a fuel container.

3. An internal combustion engine for portable powerdriven tools and the like, comprising a casing enclosing said engine and forming the supporting structure thereof, said casing being divided into two halves along a substantially medial plane, each of said halves having cavities formed therein which are open towards said plane, said cavities forming the engine crank case, a space for receiving a fuel container and a space for receiving a lubricant container.

4. An internal combustion engine as claimed in claim 3, wherein said fuel and lubricant containers are made of plastic material.

5. An internal combustion engine for portable powerdriven tools and the like, comprising a casing enclosing said engine and forming the supporting structure thereof, said casing being divided into two halves along a substantially medial plane, each of said halve having cavities formed therein which are open towards said plane, said cavities forming the engine crank case and a space adjacent thereto for receiving a fuel container and a lubricant container both made of plastic material, said lubricant container being disposed between said crank case forming space and said fuel container.

References Cited in the file of this patent UNITED STATES PATENTS 2,479,750 Lewandowski Aug. 23, 1949 FOREIGN PATENTS 809,267 Germany July 26, 1951 

